With conventional direction finding systems the smallest possible beam width and hence the resolution not only depends on the wavelength and the wave propagation speed in the medium but primarily on the geometric dimensions of the receiving or transmitting array i.e. more the aperture. The shorter the wave length and the larger the antenna dimensions, the better the beam can be focussed. If the antenna consists of several individual transducers, it is not only possible to tilt the main direction of the antenna pattern by phase shifting the control signals or received signals, but also to influence the beam width and the side lobe suppression to a given amount by time delays.
From DE 42 09 352 C2 and from the book "Secondary Radar" by P. Honold, Siemens AG, 19971 p.45 to 48 it is known to achieve a better focussing of the antenne pattern by forming the difference between a summation pattern of two closely adjacent antennas and a corresponding differential pattern.
Furthermore, in the book "Introduction to Monopulse" by D. R. Rhodes, McGraw-Hill Book Company Inc., New York 1959, a method is described, where the summation signal is generated by summing up all transducer signals and subsequently deriving a magnitude or absolute value signal. By subsequently forming the difference between said summation signal and the differential signal the main lobe becomes narrower, but strong first side lobes appear at an angular distance of 10.degree. at both sides of the central main lobe.